Self contained air conditioner



June 30, 1964 o. J. WIGGINS ETAL SELF CONTAINED AIR CONDITIONER 2 Sheets-Sheet 1 Filed April 16, 1962 INVENTORS 0 WA D J.WIGGINS R ERT G.MINER ,g vflw FIG.2

ATTORNEYS June 30, 1954 o. J. WIGGINS ETAL 3,138,940

SELF CONTAINED AIR CONDITIONER Filed April 16, 1962 2 Sheets-Sheet 2 FIG.3

FIG.4

INVENTORS OSWALD J. WIGGINS ROBERT G. MINER BY v! ATTORNEYS 3,138,941) SELF CONTAINED AIR CONDITIONER Oswald J. Wiggins and Robert G. Miner, La Crosse, Wis., assignors to The Trane Company, La Crosse, Wis., a corporation of Wisconsin Filed Apr. 16, 1962, Ser. No. 187,598 Claims. (Cl. 62-174) This invention relates to self contained air conditioning units and more particularly to a self contained air conditioner which provides a means to maintain capacity of the unit under low ambient air conditions.

An object of the invention is to provide a compact self contained air conditioning unit which is efficient in operation and is readily assembled.

Another object of the invention is to provide a compact self contained air conditioner which maintains proper head pressure when the condenser coolant is below a predetermined minimum.

A third object of the invention is to provide a self contained air conditioning unit which locates the receiver in the recirculated air stream in order to maintain proper head pressure under low condenser coolant conditions.

A still further object of the invention is to provide a self contained air conditioning unit which locates the receiver in the recirculated air stream in order to flood the condenser when the temperature of the condenser coolant is below a predetermined minimum.

A fifth object of the invention is to provide a self contained air conditioning unit in which the receiver is located in the recirculated air stream to flood the condenser in order to maintain proper head pressure when the temperature of the ambient air passing over the air cooled condenser is below a predetermined minimum.

Other objects and advantages of our invention will be clearly apparent as the specification proceeds to describe the invention with reference to the accompanying drawings, in which:

FIGURE 1 is a front elevational view with parts broken away to show details of the invention;

FIGURE 2 is a cross-sectional view taken on line 2-2 of FIGURE 1;

FIGURE 3 is a rear elevational view of the air conditioning unit shown in FIGURE 1; and

FIGURE 4 is a schematic view showing the refrigeration circuit employed in our novel air conditioning unit.

Looking now to the drawings, the reference numeral 16 represents the casing of the self contained air conditioner of this invention. Partition 12 separates casing into a condenser compartment 14 and an evaporator compartment 16.

Partition member 18 supports motor 28 which drives a pair of fan wheels 22 to effect a circulation of ambient outside air through the condenser compartment 14. Ambient air is induced through grille 24, inlet screen 26, condenser 28 to condense the refrigerant therein, and is then drawn intofan inlets 30. This induced air is then discharged through condenser discharge opening 32 and grille 24 into the atmosphere.

Evaporator fans 34 driven by motor 36 mounted on structural member 38 discharge induced air through evaporator 40 and discharge register 42 into the space to be conditioned. The evaporator 40 performs the normal function of extracting heat from the air drawn into the fan inlets 44 and discharged through the evaporator. In normal operation, return or recirculated air from the conditioned space is drawn through return register 46, over receivers 48 for reasons to be explained hereinafter, and through filters 50 into fan inlets 44.

A fresh air inlet 52 is provided in the rear of casing 10 to allow the mixture of return or recirculated air with fresh air to satisfy the ventilation requirements of the United States Patent 0 3,138,940 Patented June 30, 1964 space being conditioned. A damper 54 biased to the closed position by any suitable means is provided to control the amount of air entering the evaporator compartment 16 through the fresh air inlet 52.

When additional fresh air is desired, pull chain 56 attached to damper 54 is disengaged from a notch, not shown, in the front of casing 10 exposed to the conditioned space and pulled outwardly from the front of casing 10 into the conditioned space causing the damper to be opened to the desired position allowing more fresh air to enter the evaporator compartment. When the damper 54 has been opened the desired amount, the chain 56 is re-engaged in the notch, not shown.

It should be noted that the fresh air inlet 52 is located between the receivers 48 so that the fresh air introduced does not impinge directly upon the receivers. Damper 54 further directs the fresh air towards the fan inlets 44 so that the temperature of the incoming fresh air does not adversely affect the operation of the receivers when the outside air temperature is below a predetermined minimum temperature.

Looking now to FIGURE 4, the operation of the refrigeration cycle will be explained. Compressor 58, of any conventional type, located in the condenser compart ment 14 discharges hot compressed refrigerant into condenser 28. The refrigerant, after being condensed in the condenser 28, is expanded through expansion valve 60 into the evaporator 42 where it absorbs heat from the air passing over the evaporator. The refrigerant then passes back to the compressor Via suction line 62 and the cycle is then repeated.

In a normal system with the compressor located in the condenser compartment, the head pressure will decrease as the ambient air temperature induced over the condenser decreases. In many applications it is necessary to operate the air conditioning system the year around resulting in operation of the system when the ambient air temperature is considerably below 40 F. This low ambient air temperature results in a very low head pressure causing a low pressure differential across the expansion valve resulting in reduced capacity of the evaporator.

To alleviate this situation, receivers 48 are located in the recirculated air stream from the conditioned space prior to contact with the evaporator. In normal summer operation, the level of liquid refrigerant in the receiver 48 will be high since the receiver 48 will be at a lower temperature than the condenser 28 because the ambient air temperature is higher than the recirculated air temperature causing the pressure in the condenser to be considerably higher than the pressure in the receiver.

As the ambient air temperature decreases, the level of refrigerant in the receiver 48 will decrease causing the level of liquid refrigerant in the condenser to rise and thereby reduce some of the effective condensing surface of the condenser. This rise in level of liquid refrigerant in the condenser will tend to cause the head pressure to remain at a fairly constant level.

It can be seen that when the ambient air temperature is excessively low the receiver 48 will be almost empty and the condenser 28 will be almost completely flooded until the head pressure builds up to a point Where it exceeds the pressure in the receiver causing the condenser to dump the liquid therein and force liquid back up into the receiver. Then as the head pressure goes down again, the condenser will once again flood, build up the head pressure, and dump. This process will automatically repeat itself as long as necessary.

It can be seen that the new and improved head pressure control depends and is directly responsive to the difference in temperature between the recirculated air from the conditioned space and the temperature of the ambient air over the condenser. The respective temperatures cause the difference in pressure between the receiver and the condenser thereby controlling the level of regrigerant in these two components.

The number of receivers used depends merely upon the space requirements, cost of the components, and the amount of liquid refrigerant required to flood the condenser under extreme temperature conditions.

The above described self contained air conditioning unit provides a compact structure which incorporates a unique head pressure control that automatically compensates for an increase or decrease in the temperature of the condenser coolant. The new and improved unit also provides structure which protects the receivers from direct exposure to the outside air when fresh air is required in the conditioned space.

Although we have described in detail the preferred embodimentof our invention, it is contemplated that many changes may be made without departing from the scope or spirit of our invention and we desire to be limited only by the claims.

We claim:

1. A self contained air conditioning unit comprisin a casing, means dividing said easing into a condenser compartment and an evaporator compartment, means forming a recirculated air opening and a discharge opening in said casing in communication with said evaporator compartment, first fan means in said evaporator compartment to circulate air from said recirculated air opening to said discharge opening, means forming an inlet opening and an outlet opening in said casing in communication with said condenser compartment, second fan means in said condenser compartment to circulate air from said inlet to said outlet, an evaporator in said evaporator compartment downstream of said recirculated air opening and upstream of said discharge opening,a condenser in said condenser compartment disposed downstream of said inlet and upstream of said outlet, a compressor, means interconnecting said compressor, condenser, and evaporator in operative relationship, a receiver means connected to the outlet of said condenser and disposed upstream of said evaporator and downstream of said recirculated air opening to maintain proper head pressure under low ambient temperature conditions and a fresh air opening in said casing in communication with said evaporator compartment upstream of said evaporator and downstream of said receiver.

2. A self contained air conditioning unit comprising: a casing, means dividing said easing into a condenser compartment and an evaporator compartment, means forming a recirculated air opening and a discharge opening in said casing in communication with said evaporator compartment, first fan means in said evaporator compartment to circulate air from said recirculated air opening to said discharge opening, means forming an inlet opening and an outlet opening in said casing in communication with said condenser compartment, second fan means in said condenser compartment to circulate air from said inlet to said outlet, an evaporator in said evaporator compartment downstream of said recirculated air opening and upstream of said discharge opening, a condenser in said condenser compartment disposed downstream of said inlet and upstream of said outlet, a compressor in said condenser compartment, means interconnecting said compressor, condenser, and evaporator in operative relationship, and receiver means connected to the outlet of said condenser 4 and disposed upstream of said evaporator and downstream of said recirculated air opening to maintain proper head pressure under low ambient temperature conditions, said first fan means being disposed downstream of said receiver means and said recirculated air opening.

3. A self contained air conditioning unit comprising: a casing, means dividing said easing into a condenser compartment and an evaporator compartment, means forming a recirculated air opening and a discharge opening in said casing in communication with said evaporator compartment, first fan means in said evaporator compartment to circulate air from said recirculated air opening to said discharge opening, means forming an inlet opening and an outlet opening in said casing in communication with said condenser compartment, second fan means in said condenser compartment to circulate air from said inlet to said outlet, an evaporator in said evaporator compartment between said recirculated air opening and said discharge opening, a condenser in said condenser compartment between said inlet and said outlet, a compressor, means interconnecting said compressor, condenser, and evaporator in operative relationship, a fresh air opening in said casing in communication with said evaporator compartment, receiver means connected to the outlet of said condenser and located between said evaporator and said recirculated air opening to maintain proper head pressure under low ambient temperature conditions, and a damper controlling the flow of air through said fresh air opening and bypassing said fresh air around said receiver means.

4. A self contained air conditioning unit comprising: a casing, means dividing said easing into a condenser compartment and an evaporator compartment, means forming a recirculated air opening and a discharge opening in said casing in communication with said evaporator compartment, first fan means in said evaporator compartment to circulate air from said recirculated air opening to said discharge opening, means forming an inlet opening and an outlet opening in said casing in communication with said condenser compartment, second fan means in said condenser compartment to circulate air from said inlet to said outlet, an evaporator in said evaporator compartment between said recirculated air opening and said discharge opening, a condenser in said condenser compartment between said inlet and said outlet, a compressor in said condenser compartment, means interconnecting said compressor, condenser and evaporator in operative relationship, a fresh air opening in said casing in communication with said evaporator compartment, receiver means connected to the outlet of said condenser and located between said evaporator and said recirculated air opening to maintain proper head pressure under low ambient temperature conditions, and a damper controlling the flow of air through said fresh air opening and bypassing said fresh air around said receiver means.

5. The structure of claim 4 wherein said receiver means comprises a pair of receivers, one of said receivers being on one side of said fresh air opening and the other receiver being on the other side of said fresh air opening, said damper being located between said receivers.

References Cited in the file of this patent UNITED STATES PATENTS 

2. A SELF CONTAINED AIR CONDITIONING UNIT COMPRISING: A CASING, MEANS DIVIDING SAID CASING INTO A CONDENSER COMPARTMENT AND AN EVAPORATOR COMPARTMENT, MEANS FORMING A RECIRCULATED OPENING AND A DISCHARGE OPENING IN SAID CASING IN COMMUNICATION WITH SAID EVAPORATOR COMPARTMENT, FIRST FAN MEANS IN SAID EVAPORATOR COMPARTMENT TO CIRCULATE AIR FROM SAID RECIRCULATED AIR OPENING TO SAID DISCHARGE OPENING, MEANS FORMING AN INLET OPENING AND AN OUTLET OPENING IN SAID CASING IN COMMUNICATION WITH SAID CONDENSER COMPARTMENT, SECOND FAN MEANS IN SAID CONDENSER COMPARTMENT TO CIRCULATE AIR FROM SAID INLET TO SAID OUTLET, AN EVAPORATOR IN SAID EVAPORATOR COMPARTMENT DOWNSTREAM OF SAID RECIRCULATED AIR OPENING AND UPSTREAM OF SAID DISCHARGE OPENING, A CONDENSER IN SAID CONDENSER COMPARTMENT DISPOSED DOWNSTREAM OF SAID INLET AND UPSTREAM OF SAID OUTLET, A COMPRESSOR IN SAID CONDENSER COMPARTMENT, MEANS INTERCONNECTING SAID COMPRESSOR, CONDENSER, AND EVAPORATOR IN OPERATIVE RELATIONSHIP, AND RECEIVER MEANS CONNECTED TO THE OUTLET OF SAID CONDENSER AND DISPOSED UPSTREAM OF SAID EVAPORATOR AND DOWNSTREAM OF SAID RECIRCULATED AIR OPENING TO MAINTAIN PROPER HEAD PRESSURE UNDER LOW AMBIENT TEMPERATURE CONDITIONS, SAID FIRST FAN MEANS BEING DISPOSED DOWNSTREAM OF SAID RECEIVER MEANS AND SAID RECIRCULATED AIR OPENING. 